Considering that self-help publishing pulls in more than $10 billion in profits annually, the news has generated waves in an industry that critics are wont to puncture.

For the small pilot study, researchers tested 30 participants, half of whom read self-help books and half of whom did not. The half who did read the genre were further divided into those who read problem-oriented books that explore personal challenges, such as divorce, and those who read growth-oriented books that promote inspirational messages about life and happiness.

The results: Participants who read problem-focused self-help books had more depressive symptoms and those who read growth-oriented self-help books had higher stress reactivity compared to those who didn't read this genre.

"[O]ur results show that while consumers of certain types of self-help books secrete higher levels of cortisol [a stress hormone] when confronted with stressful situations, consumers of another type of self-help books show higher depressive symptomatology compared to non-consumers," Sonia Lupien, Director of the Centre of Studies on Human Stress (CSHS) at the University of Montreal, said in a statement.

In an op-ed in The Wall Street Journal, Steve Salerno, author of "Sham: How the Self-Help Movement Made America Helpless," suggests a possible cause for the stress associated with the books.

Today, anyone – not just scientifically-trained professionals – can write a self-help book, he says.

"Though modern self-help had its origins in works by classically trained psychiatrists ... today's leading exponents have as much business trading in mental health as they do performing neurosurgery," Mr. Salerno writes. "They're snake-oil salesmen, pitching regimens that have never been validated."

Does reading self-help books make a reader more stressed out and depressed – or are stressed, depressed people simply more likely to read self-help books? Both, in fact, are possible, according to the study's researchers, and further studies may investigate this.

Of course, many readers of self-help books insist that these titles have changed their lives for the better. But Ms. Lupien argues that the benefit may be smaller than the industry's $10-billion price tag would suggest.

"It seems that these books do not produce the desired effects," she says.